Kanamycin is known to interact with the diuretic ethacrynic acid to produce severe cochlear destruction. This study is designed to determine ultrastructural changes in cochlear tissues produced by this interaction. The status of the interaction will be followed by monitoring the known effects of this interaction on the AC cochlear potential. Cochlear samples for electronmicroscopy examination will be obtained at selected times before, during and after the interaction. In addition, measures of the DC endolymphatic potential as well as the concentration of kanamycin and ethacrynic acid in plasma, perilymph and endolymph will be made. Aminoglycoside antibiotics are known to interact with the loop inhibition diuretics to produce severe cochlear destruction. As an experimental model of this interaction we are studying the interaction between the aminoglycoside antibiotic kanamycin and the loop inhibiting diuretic ethacrynic acid.